Cattle that had not been tested for BSE were allowed to slip into the human food chain, a study has concluded.
An estimated 261 cattle have not been tested this year
The Food Standards Agency launched an inquiry in June after it emerged that some sick and injured animals had not been subjected to proper checks.
However, the report published on Monday, suggests that the risk of contracting BSE from these animals was "very low".
And it says the main safeguards against BSE were working well.
The alarm was raised last year by the Meat Hygiene Service (MHS), a body which enforces inspection and welfare regulations in slaughterhouses.
It found that two so-called "casualty cattle" - sick or injured animals - had not been tested at a plant in Scotland. More cases were detected in April this year.
The MHS later established that 55 abattoirs across Britain had failed to test 261 animals since January.
The inquiry by the Food Standard Agency has been supervised by a group of experts led by Patrick Wall, Professor of Food Safety at University College, Dublin.